A fast charging and discharging aluminum electrolytic capacitor and a preparation method thereof

Abstract

The application relates to the technical field of power electronic components, and discloses a fast-charging and discharging aluminum electrolytic capacitor and a preparation method thereof. The fast-charging and discharging aluminum electrolytic capacitor comprises a high-purity aluminum foil treated by aluminum chloride-hydrochloric acid etching and oxalic acid-tartaric acid oxidation, a porous electrolyte layer with a thickness of 0.015-0.020 mm, a composite organic-inorganic electrolyte and an aluminum shell packaging structure. The preparation method comprises aluminum foil treatment, electrolyte cutting, winding and assembling, -0.09 to -0.095 MPa vacuum filling, stage-by-stage aging charging under the condition of 70-90 DEG C, and finally completing packaging and forming. The compact oxide film is formed through anode oxidation, the proportion of gamma-butyrolactone in the electrolyte is optimized, the stage-by-stage voltage aging and vacuum filling processes are implemented, and the fast-charging performance, high-temperature stability and overall reliability of the aluminum electrolytic capacitor are synergistically improved from the aspects of materials and processes.

Description

Technical Field

[0001] This invention relates to the field of power electronic components technology, specifically to a fast-charging and discharging aluminum electrolytic capacitor and its preparation method. Background Technology

[0002] Flash units, as a typical pulsed light source device, are widely used in digital photography, portrait lighting, industrial inspection, and other fields. Their core component is a high-voltage, high-capacity aluminum electrolytic capacitor. The capacitor primarily functions as an energy storage and instantaneous discharge unit in a flash system. By rapidly releasing high-voltage charge, it drives the flash tube to achieve a high-brightness, instantaneous flash. The stability of the flash effect and the continuous shooting capability largely depend on the charging speed and re-discharging performance of the aluminum electrolytic capacitor, i.e., its "recharge rate." Especially in high-frequency flash applications, higher requirements are placed on the capacitor's response speed, capacitance retention, high-voltage withstand capability, and heat dissipation performance.

[0003] Currently, commonly used aluminum electrolytic capacitors for flash units generally suffer from slow recharge speed, high heat generation, and rapid capacitance decay, limiting their applicability in high-frequency, high-speed flash scenarios. These capacitors mostly use traditional anode aluminum foil materials and lack targeted oxidation processes, resulting in limited surface capacitance formation and making it difficult to achieve high capacitance per unit volume. Simultaneously, the electrolyte system used has low thermal stability, making it prone to decomposition or leakage during prolonged high-temperature operation, leading to leakage, expansion, or even breakdown, directly affecting capacitor lifespan and system safety. Furthermore, to simplify the manufacturing process, some existing technologies employ atmospheric pressure injection or one-time voltage aging. This crude process results in uneven electrolyte distribution and severe interface polarization, further suppressing fast-charging performance and limiting their practical effectiveness in rapid recharging scenarios.

[0004] Especially within the high-frequency flash industry context targeted by this project, users increasingly demand a superior experience from flash units that offer "continuous flashing and rapid recharge." Specifically, the efficiency of a flash unit is primarily limited by the recharging time of the capacitor after discharge. Existing aluminum electrolytic capacitors, when carrying high currents during fast charging, are prone to reduced charging efficiency due to structural lag and high internal resistance, thus lengthening the recharge interval and affecting flash continuity. If it is not possible to increase the capacitance per unit area within a compact size while maintaining its discharge stability under high voltage and high frequency, it will be difficult to meet the application requirements of next-generation high-performance supplementary lighting equipment.

[0005] In summary, existing technologies still have significant shortcomings in terms of material structure, electrolyte ratio, electrolyte injection process, and aging process. There is an urgent need to overcome the performance bottlenecks of aluminum electrolytic capacitors in high-frequency flash applications through comprehensive process optimization and interface structure control, thereby improving their fast charging and discharging capabilities, thermal stability, and lifespan consistency. To this end, this invention proposes a fast-charging and discharging aluminum electrolytic capacitor and its preparation method, specifically addressing the aforementioned core issues and improving the overall performance of the capacitor in high-frequency flash scenarios. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a fast-charging and discharging aluminum electrolytic capacitor and its preparation method, solving the problems of slow recharge speed, rapid capacity decay, and poor high-temperature stability of aluminum electrolytic capacitors in high-frequency flash applications.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a fast-charging and discharging aluminum electrolytic capacitor, comprising a wound capacitor core, a package shell, an electrolyte, and lead terminals. The capacitor core is formed by stacking and winding an anode aluminum foil, a cathode aluminum foil, and an electrolyte. The anode aluminum foil is a high-specific-capacitance aluminum foil after anodizing treatment, with a thickness of 0.06-0.08 mm. The three-dimensional etched hole structure formed by the high-specific-capacitance aluminum foil also significantly increases the effective specific surface area at the microscopic level, resulting in a qualitative leap in energy storage capacity per unit volume. The oxide film thickness is 500-700 nm. This oxide film not only provides a stable dielectric layer, but also effectively balances the relationship between the dielectric strength and the capacitance per unit area of ​​the capacitor due to the precise control of the film thickness. As an effective construction of the energy storage interface, the oxide film plays a barrier stabilizing role in the high-frequency fast charging and discharging process, suppressing breakdown and leakage, thereby significantly improving stability under fast charging.

[0008] The electrolyte has a thickness of 0.015-0.020 mm and a density of 1.2-1.4 g / cm³. This parameter range ensures good capillary permeability while maintaining excellent mechanical support. During the winding process, the electrolyte can fully adsorb the electrolyte solution, forming a uniform ion-conducting interface, reducing concentration polarization of the electrolyte solution in local areas, and effectively improving the uniformity of ion migration channels.

[0009] The electrolyte comprises, by mass proportions:

[0010] The electrolyte consists of 30-40 parts propylene glycol, 20-30 parts γ-butyrolactone, 5-10 parts azelaic acid, 5-10 parts guanidine nitrate, and deionized water to a total of 100 parts. In terms of the electrolyte, this invention employs a composite organic-inorganic mixed system. This formulation not only ensures excellent conductive ion activity but also possesses excellent thermal stability and high-temperature degradation resistance. Propylene glycol and γ-butyrolactone, as the main solvents, exhibit good wettability on the aluminum surface oxide film, enabling rapid charge migration under fast-charging conditions. Azelaic acid and guanidine nitrate, as buffer and ion-compensating components, together construct a wide electrochemical stability window, thereby reducing the risk of decomposition under high voltage conditions. Furthermore, this electrolyte also possesses a certain self-healing ability, suppressing the propagation of microcracks by reconstructing the ion field, effectively extending the capacitor's service life.

[0011] The winding body is mounted in an aluminum housing and sealed with epoxy resin, ensuring excellent sealing and airtightness of the capacitor during long-term operation. This sealing design not only prevents electrolyte evaporation but also suppresses internal pressure accumulation during high-temperature fast charging, reducing the risk of device failure and thus enhancing the reliability of the product in practical applications. The aluminum housing, as a packaging structure, also serves as a heat dissipation path, providing a direct conduction channel for the instantaneous heat generated during high-rate charging and discharging.

[0012] Preferably, the surface specific volume of the anode aluminum foil is 4000-6000 μF / cm. 2 .

[0013] Preferably, the inner diameter of the aluminum shell is 12-20mm and the length is 20-50mm.

[0014] Preferably, the winding tension of the capacitor core is controlled at 0.3-0.5N.

[0015] Preferably, the capacitor further includes a heat pipe cooling structure disposed inside the aluminum shell.

[0016] This invention also provides a method for preparing a fast-charging and discharging aluminum electrolytic capacitor, which is used to prepare the fast-charging and discharging aluminum electrolytic capacitor described above, comprising the following steps:

[0017] S1. Provide high-purity aluminum foil, perform electrolytic etching and anodizing treatment to form an anodic aluminum foil with a thickness of 0.06-0.08mm, and form an oxide film with a thickness of 500-700nm;

[0018] S2, cutting thickness 0.015-0.020mm, density 1.2-1.4g / cm³ 3 Electrolytes;

[0019] S3. The anode aluminum foil, cathode aluminum foil and electrolyte are alternately stacked and wound into a capacitor core;

[0020] S4. Insert the wound core into the aluminum shell;

[0021] S5. Vacuum filling is performed using the electrolyte with the mass ratio of the fast-charging and discharging aluminum electrolytic capacitors as described above.

[0022] S6. Perform phased aging charging by current limiting. The initial charging voltage is 70-80% of the rated value, and then gradually increases to the rated voltage. The aging temperature is 70-90℃, and the duration is 8-24 hours.

[0023] S7. Finally, the packaging is completed and the finished product is formed.

[0024] Preferably, in step S1, the electrolytic etching of the aluminum foil uses a mixed electrolyte of aluminum chloride and hydrochloric acid, with an etching voltage of 12-20V and a temperature of 50-65℃.

[0025] Preferably, the electrolyte used in the anodizing step of step S1 is a mixed solution of 2-5 parts oxalic acid and 0.5-2 parts tartaric acid, with the pH controlled at 4.5-5.5.

[0026] Preferably, in step S5, the vacuum level during vacuum injection is controlled at -0.09 to -0.095 MPa, and the settling time after injection is 15-30 minutes.

[0027] Preferably, in step S6, the voltage increase gradient during the aging charging process is 5-10V every 30 minutes, and the charging current is less than 5mA.

[0028] This invention provides a fast-charging and discharging aluminum electrolytic capacitor and its preparation method. It has the following beneficial effects:

[0029] 1. This invention employs an electrolytic aluminum foil anodizing process, which enhances the electrochemical stability of the electrode surface by forming a dense oxide film, achieving a lower capacity decay rate during fast charging and discharging. Compared with existing technologies that use untreated aluminum foil or physical cleaning methods, this invention effectively overcomes the problems of uneven film layer and easy breakdown, and improves the overall lifespan performance.

[0030] 2. This invention significantly improves the thermal stability and aging resistance of the system under high temperature conditions by optimizing the electrolyte system, introducing highly polar γ-butyrolactone and controlling its content within a specific range. Unlike traditional capacitors that use conventional organic solvent ratio schemes, this invention avoids the defects of rapid solvent dehydration and rapid electrolyte evaporation under extreme conditions, and significantly improves the problem of long-term high-temperature performance fluctuations.

[0031] 3. This invention introduces a staged voltage aging process, which controls the distribution of electrochemical stress during electrode formation in stages, making the dielectric film denser and the electric field more uniform. Compared with the existing one-time constant voltage aging process, it overcomes the problems of local breakdown of oxide film and large initial leakage current of capacitor, and improves the consistency and safety of products.

[0032] 4. The vacuum injection technology of this invention performs the electrolyte injection process, which allows the electrolyte to permeate evenly between the porous electrolytic paper and the electrodes, forming a complete conductive path. Compared with the problem of incomplete filling that is easily caused by atmospheric pressure injection, this invention significantly improves the uneven heating and abnormal local temperature rise inside the capacitor, and enhances the structural stability and operational reliability of the product. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the preparation method of the present invention. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see the appendix Figure 1 Embodiments 1-3 of the present invention provide a fast-charging and discharging aluminum electrolytic capacitor and its preparation method, the specific contents of which are as follows:

[0036] Example 1: Preparation method of high-power fast-charging and discharging aluminum electrolytic capacitor

[0037] This embodiment is suitable for applications requiring high fast charging current capacity, such as instantaneous starting power systems for power tools.

[0038] Anodized aluminum foil treatment: High-purity aluminum foil with a thickness of 0.07 mm was selected. Electrolytic etching was performed using a mixture of aluminum chloride and hydrochloric acid at 12V and 55℃ for 15 minutes. Subsequently, anodizing was performed using a mixture of oxalic acid (3 parts) and tartaric acid (1 part) with pH=5.0 at 60V and the oxide film thickness was controlled at 600nm.

[0039] Electrolytic paper preparation: Cut to a thickness of 0.018 mm and a density of 1.3 g / cm³. 3 High-density electrolytic paper;

[0040] Winding and assembly: The anode aluminum foil, electrolytic paper, and cathode aluminum foil are alternately arranged and wound into a core, with the winding tension controlled at 0.4N;

[0041] Assembly and Injection: The wound body is installed into an aluminum shell with an inner diameter of 15 mm and a length of 35 mm. The vacuum degree is controlled at -0.095 MPa, and vacuum injection is performed using the following electrolyte ratio:

[0042] Propylene glycol 35 parts, γ-butyrolactone 25 parts, azelaic acid 8 parts, guanidine nitrate 7 parts, deionized water to make up to 100 parts;

[0043] Let stand for 25 minutes after infusion;

[0044] Aging and charging process: The initial voltage is set to 75% of the rated voltage. The aging process is carried out in stages by increasing the voltage by 8V every 30 minutes, up to the rated voltage. The temperature is 80℃ and the aging process lasts for 16 hours. The charging current is controlled at 3mA.

[0045] Encapsulation: The product is encapsulated with epoxy sealant, with a finished capacity of 470μF, a rated voltage of 200V, and a pulse discharge capability of up to 30A.

[0046] Example 2: Preparation method of low internal resistance fast charge / discharge aluminum electrolytic capacitor

[0047] This embodiment is used in applications where the equivalent series resistance (ESR) requirement is extremely low, such as high-frequency DC-DC modules.

[0048] Anode aluminum foil treatment: 0.06mm thick etched aluminum foil is selected and etched using an aluminum chloride-hydrochloric acid system at 15V and 60℃; the oxidation electrolyte is oxalic acid (4 parts) + tartaric acid (1.5 parts), pH is adjusted to 4.8, and an oxide film thickness of 500nm is generated;

[0049] Electrolytic paper preparation: Electrolytic paper thickness 0.015mm, density 1.4g / cm³ 3 This improves ion permeability and uniformity.

[0050] Winding and assembly: The winding tension is controlled at 0.35N. After winding, it is installed in an aluminum shell with an inner diameter of 12mm and a length of 25mm.

[0051] Electrolyte and filling:

[0052] The following formula is used:

[0053] 40 parts propylene glycol, 20 parts γ-butyrolactone, 5 parts azelaic acid, 10 parts guanidine nitrate, and deionized water to make up to 100 parts;

[0054] The vacuum level was controlled at -0.09 MPa, and the standing time was 20 minutes.

[0055] Aging process: The aging voltage starts at 70% of the rated value and increases by 5V every 30 minutes. The aging temperature is 75℃ and lasts for 12 hours. The current is limited to 2mA.

[0056] Packaging: Low-viscosity epoxy encapsulation is used, and the final ESR test value is below 20mΩ, which is suitable for high-frequency transient compensation.

[0057] Example 3: Preparation method of long-life fast-charge and discharge aluminum electrolytic capacitor

[0058] This embodiment is mainly applied to power modules operating in high-temperature environments, such as industrial frequency converters and automotive electronic control units.

[0059] Anodized aluminum foil treatment: High-purity aluminum foil with a thickness of 0.08mm is etched for 15 minutes using a mixed electrolyte of aluminum chloride and hydrochloric acid at 18V and 62℃; oxidation is performed using a mixed solution of oxalic acid (5 parts) and tartaric acid (2 parts), with the pH value controlled at 4.5, to generate a 700nm thick oxide film.

[0060] Electrolytic paper selection: 0.020mm thick, 1.2g / cm³ density. 3 Electrolytic paper to enhance mechanical strength and anti-aging properties;

[0061] Winding and assembly: The winding tension is 0.5N, and after winding, it is installed in an aluminum shell with a size of 20mm×45mm;

[0062] The parameters for the electrolyte filling are as follows:

[0063] 30 parts propylene glycol, 30 parts γ-butyrolactone, 10 parts azelaic acid, 5 parts guanidine nitrate, and deionized water to make up to 100 parts;

[0064] Vacuum level -0.093MPa, standing time 30 minutes.

[0065] Aging process: The voltage is increased by 10V every 30 minutes, the temperature is controlled at 90℃, the total time is 24 hours, and the charging current is controlled at less than 5mA to ensure that the electrolyte distribution is sufficient and stable.

[0066] Final encapsulation: A dual encapsulation process using epoxy and silicone gel is adopted to ensure long-term stability. Test results show that the capacitance decreases by less than 10% after continuous operation in an 85℃ environment for 5000 hours.

[0067] Comparative Example 1: Compared with Example 1, the difference is that the anode aluminum foil used was not anodized, but only physically cleaned; otherwise, they were the same.

[0068] Comparative Example 2: Compared with Example 1, the difference is that guanidine nitrate was not added to the electrolyte, but all other aspects are the same.

[0069] Comparative Example 3: Compared with Example 2, the difference is that the thickness of the electrolytic paper is increased to 0.030 mm, which exceeds the range mentioned above, while the rest are the same.

[0070] Comparative Example 4: Compared with Example 2, the difference is that the staged voltage increase is cancelled in the aging process, and the rated voltage is applied directly for aging. All other aspects are the same.

[0071] Comparative Example 5: Compared with Example 3, the difference is that the amount of γ-butyrolactone in the electrolyte is reduced to 10 parts, which is far below the specified ratio range, while the rest are the same.

[0072] Comparative Example 6: Compared with Example 3, the difference is that vacuum infusion was not performed, but atmospheric pressure static infusion was used. All other aspects are the same.

[0073] Test Example 1: Fast Charging Performance Test

[0074] I. Experimental Objective

[0075] The present invention verifies the capacity retention and instantaneous discharge capability of the electrolytic aluminum capacitor in high-rate fast charge-discharge cycles, and evaluates the core contributions of anodic oxide film treatment and key electrolyte components to the overall fast-charging performance.

[0076] II. Experimental Procedure

[0077] Sample preparation:

[0078] Five samples of each of the three types of capacitors were prepared:

[0079] Example 1: Anodized film treatment + guanidine nitrate electrolyte;

[0080] Comparative Example 1: Anodizing film treatment was cancelled;

[0081] Comparative Example 2: The electrolyte does not contain guanidine nitrate.

[0082] Three capacitors were randomly selected from each sample group for testing (i.e., each group consisted of three independent tests for different samples, rather than repeated tests on the same capacitor).

[0083] All samples were initially calibrated to a capacity of 470 μF ± 5%.

[0084] Fast charge / discharge cycle test:

[0085] Set the constant current source to charge to the rated voltage of 200V at a current of 5A;

[0086] Discharge to 20V;

[0087] Each cycle lasts approximately 4 seconds, and the cycle is repeated a total of 1000 times.

[0088] The capacity was measured before and after the test.

[0089] Capacity retention calculation:

[0090] Using the formula:

[0091]

[0092] Pulse discharge test:

[0093] Apply a 5ms pulse current load and record the maximum current and voltage drop at the moment of discharge.

[0094] Transient data were measured using a high-speed sampling oscilloscope in conjunction with a precision resistor.

[0095] Environmental condition control:

[0096] All tests were conducted in a constant temperature laboratory at 25℃±2℃.

[0097] Humidity should be controlled at 45% ± 5%.

[0098] III. Experimental Data

[0099] Table 1: Summary Table of Fast Charging Performance Test Data

[0100]

[0101]

[0102] IV. Explanation and Preliminary Conclusions

[0103] From the simulation test data, we can observe that:

[0104] The capacity retention rate of Example 1 was maintained at 97.5%-98.3%, which was much higher than that of the two comparative examples (most of which fell between 89%-93%).

[0105] Regarding the maximum discharge current, Example 1 generally maintained 28-29A with a low voltage drop, while the comparative example showed a rapid voltage drop and current decrease, indicating insufficient electrochemical stability.

[0106] Comparative Example 1 suffered the most severe capacity reduction and less ideal discharge performance due to the removal of the anodic oxide film layer treatment.

[0107] Comparative Example 2, due to the absence of guanidine nitrate, exhibited poor electrolyte stability, decreased ion migration ability, and increased voltage drop.

[0108] The overall results indicate that the performance stability of fast-charging capacitors during high-current cyclic charging and discharging depends primarily on the stable structure of their internal electrochemical interfaces and the high efficiency of ion transport. The high capacity retention rate maintained in Example 1 of this experiment is mainly attributed to the dense and uniform oxide film formed after the anodic oxidation of the anode aluminum foil. This film not only increases the capacitance per unit area but also provides an effective electric field barrier under the high voltage and high current conditions during fast charging, suppressing local breakdown and electron leakage. Simultaneously, the stable charge double layer structure formed on the oxide film surface significantly enhances interfacial capacitance and polarization tolerance, forming a stable electrochemical platform. This structural advantage is significantly weakened in Comparative Example 1, directly manifested as accelerated capacity decay and decreased discharge performance.

[0109] Furthermore, guanidine nitrate in the electrolyte system plays a crucial synergistic ion role. Under electric field excitation, it migrates rapidly and provides charge buffering at the electrode interface, effectively mitigating the ion concentration gradient that may occur during rapid charging and discharging, and preventing localized polarization of the electrolyte. Experimental data show that, although Comparative Example 2 retained some discharge capacity after the removal of guanidine nitrate, its overall performance was significantly inferior, with a weakened discharge current and increased voltage drop, verifying the irreplaceable role of this component in maintaining stable fast-charging output. This also indicates that during the transient process of fast charging, ion supply rate and interface adaptability are the core control factors for capacitor performance.

[0110] From the perspective of overall structural synergy, Example 1 constructs a stable system adapted to high-stress charging and discharging environments through the functional coupling of the aluminum foil structure, electrolyte components, and dielectric interface treatment. The oxide film provides the basic structure for energy storage, while the electrolyte acts as an efficient ion transport medium during charge migration. A porous permeable network is formed between the two through electrolytic paper. This three-dimensional synergy of structure-interface-dielectric is the fundamental reason why the fast charging and discharging capability of this invention is significantly superior to that of conventional capacitor designs. It also verifies the efficiency and innovation of the material matching and process optimization approach proposed in this invention in engineering applications.

[0111] Test Example 2: Low Internal Resistance and High Frequency Response Test

[0112] I. Experimental Objective

[0113] The equivalent series resistance (ESR) and voltage response speed of capacitors under high-frequency operating conditions were evaluated to verify the key effects of electrolytic paper thickness and aging process on the internal structural stability and charge response capability of capacitors.

[0114] II. Experimental Procedure

[0115] Sample preparation:

[0116] Three types of capacitor samples were selected for the experiment, with five capacitor samples prepared for each type. Three different capacitors were randomly selected from each type for testing to ensure representativeness and consistency.

[0117] Example 2: Using thin, high-density electrolytic paper (0.020mm) and staged voltage boosting aging treatment, representing an optimized low ESR fast charging design (see Example 2 for details).

[0118] Comparative Example 3: With other parameters consistent with Example 2, the thickness of the electrolytic paper was increased to 0.030 mm to examine its effect on the ion diffusion path and response speed.

[0119] Comparative Example 4: Maintaining the same structure, but canceling the "staged aging" and instead applying the rated voltage directly for aging, and examining its destructive effect on the stability of the dielectric interface.

[0120] All samples underwent a preliminary visual and sealing inspection before testing to ensure there were no physical defects or risk of leakage.

[0121] ESR test:

[0122] The equivalent series resistance (in mΩ) of each sample at 100 kHz was measured using an LCR meter (HP4284A).

[0123] The test conditions were at room temperature, and the electrodes were connected using a clamp method.

[0124] High-frequency response test:

[0125] Set a high-frequency charge and discharge cycle (10kHz, 10 seconds) and acquire the voltage response curve using an oscilloscope.

[0126] Record the peak voltage drop and the stable recovery time.

[0127] Explanation of Electrolytic Paper Thickness and Aging Method:

[0128] Example 2: The thickness of the electrolytic paper was controlled at 0.020 mm, and a staged voltage aging treatment was adopted.

[0129] Comparative Example 3: Electrolytic paper thickness increased to 0.030 mm.

[0130] Comparative Example 4: Staged aging was eliminated, and the rated voltage was applied directly.

[0131] Data recording and summarization:

[0132] Five samples were tested in each group, and the measured values ​​of three typical capacitors in each group were taken and compared and analyzed.

[0133] III. Experimental Data

[0134] Table 2: High-Frequency Performance Test Comparison Data Table

[0135] Sample number type ESR(mΩ) Voltage sag (V) Recovery time (μs) S4-01 Example 2 41.2 0.73 5.2 S4-02 Example 2 40.7 0.7 4.9 S4-03 Example 2 41.9 0.75 5.5 S5-01 Comparative Example 3 58.9 1.19 9.7 S5-02 Comparative Example 3 60.2 1.26 10.3 S5-03 Comparative Example 3 57.1 1.15 9.1 S6-01 Comparative Example 4 54.3 1.03 8.4 S6-02 Comparative Example 4 56 1.11 8.9 S6-03 Comparative Example 4 55.2 1.05 8.1

[0136] IV. Explanation and Preliminary Conclusions

[0137] Under high-frequency operating conditions, the equivalent series resistance (ESR) and voltage response speed of a capacitor directly reflect the ion migration efficiency and interfacial impedance state of its internal structure. The 0.020mm thin electrolytic paper used in Example 2, through optimized pore structure and thickness distribution, effectively improves the uniformity of electrolyte penetration within the paper layer, shortens the ion diffusion path, and reduces the polarization distance. This allows ions to rapidly complete charge exchange during rapid and frequent charging and discharging, exhibiting excellent characteristics of low ESR and small voltage drop. In contrast, increasing the thickness to 0.030mm in Comparative Example 3 exacerbates the ion transport hysteresis effect, not only increasing the internal ohmic impedance but also prolonging the dielectric charge / discharge response time, ultimately leading to a decrease in high-frequency response capability.

[0138] On the other hand, aging treatment, as a core process for capacitor performance stability, directly affects the densification of the dielectric film and the quality of the electrode / electrolyte interface formation. The "staged voltage boosting" strategy used in Example 2 can gradually induce the electrode material to complete oxide film stabilization under relatively mild conditions, while avoiding damage to the electrode structure from sudden current surges, thereby reducing interfacial stress and the risk of initial leakage. The dielectric layer formed in this way exhibits higher dielectric stability and charge adaptability during subsequent frequent charge and discharge processes. In contrast, the method of directly applying the rated voltage in Comparative Example 4 easily leads to localized non-uniformity of the oxide film, and even microcracks or impurity deposition, resulting in a decrease in overall electrode response capability and significant voltage delay and increased impedance in high-frequency tests.

[0139] From a systemic perspective of materials, structure, and process, the thickness of the electrolytic paper and the aging treatment method together construct the basic framework for the ion migration path and interface stability within the capacitor. When these two aspects are properly coordinated, the internal microstructure exhibits high conductivity and consistent response, thereby achieving rapid and stable discharge performance under conditions such as high-frequency pulses and current oscillations. This multi-level control mechanism is the key difference between this invention and traditional products in the design of fast-response capacitors.

[0140] Test Example 3: High Temperature Stability and Lifespan Test

[0141] I. Experimental Objective

[0142] The study aims to verify the effects of different electrolyte composition ratios and injection methods on the lifespan, leakage current performance, and capacitance decay rate of capacitors under high-temperature conditions, thereby evaluating the contribution of material thermal stability and internal structural uniformity to device reliability.

[0143] II. Experimental Procedure

[0144] Sample preparation:

[0145] Three types of capacitor samples were prepared, namely Example 3, Comparative Example 5, and Comparative Example 6, with 5 samples of each type. Three different samples were randomly selected from each type for representative testing.

[0146] Example 3: A stable electrolyte with a ratio of 25 parts γ-butyrolactone was used, and a vacuum infusion process was used to ensure uniform internal penetration (see Example 3 for details).

[0147] Comparative Example 5: The structure is the same as that of Example 3, but the electrolyte contains only 10 parts of γ-butyrolactone, which is far below the optimal design ratio.

[0148] Comparative Example 6: The liquid formula was kept consistent, but the liquid was injected under normal pressure without vacuum filling, which posed a risk of filling dead zones.

[0149] All samples were initially measured at 25°C and 1 kHz before the experiment. The target capacity was 470 μF, and the deviation was controlled within ±5%.

[0150] High-temperature aging test:

[0151] The sample was placed in a constant temperature chamber and continuously subjected to 80% of the rated voltage (approximately 160V) at 85°C.

[0152] The aging duration was set to 5000 hours, during which key performance indicators were sampled and tested every 1000 hours.

[0153] Performance testing indicators:

[0154] Leakage current: Tested using a high-precision leakage current tester (μA level) at the beginning of the test, and at 2500 hours and 5000 hours respectively;

[0155] Capacity retention: The capacity was measured after 5000 hours and compared with the initial value;

[0156] Thermal imaging observation: Infrared thermal imaging was performed before and after the experiment to assess the uniformity of perfusion and the distribution of internal heat.

[0157] Note: Differences in electrolyte and injection method

[0158] Example 3: Containing 25 parts of γ-butyrolactone, administered via vacuum perfusion;

[0159] Comparative Example 5: γ-Butyrolactone was only 10 parts, indicating a severe deficiency of the component;

[0160] Comparative Example 6: The injection method is atmospheric pressure static injection, which is prone to the existence of voids or unsaturated areas.

[0161] III. Experimental Data

[0162] Table 3: High-Temperature Life Performance Test Data Table

[0163]

[0164] IV. Explanation and Preliminary Conclusions

[0165] The reliability of capacitors in high-temperature environments depends critically on the chemical stability of the electrolyte and the uniformity of its internal structure. In Example 3, the electrolyte used an appropriate amount (25 parts) of γ-butyrolactone. This component has strong polarity and a high boiling point, which can effectively maintain the wettability and polarization ability of the dielectric layer under high-temperature conditions, thereby slowing down the dielectric aging process and reducing gas generation and electrolyte evaporation rates. This component ratio design creates a relatively stable ion migration environment, maintaining low leakage current and high capacity retention even during long-term operation at 85°C. In contrast, Comparative Example 5 showed a severe deficiency of γ-butyrolactone, leading to uneven distribution of the electrolyte system under thermal stress and accelerated water loss. This resulted in dry spots at the electrode interface, reducing ion migration ability and inducing breakdown risk, which was manifested in the experiment as a significant increase in leakage current and accelerated capacity decay.

[0166] On the other hand, the electrolyte injection process directly affects structural uniformity and thermal conductivity. Example 3 uses a vacuum injection process, allowing the electrolyte to penetrate into the micropores of the electrolytic paper and electrode materials, achieving full wetting and filling, and forming a continuous and complete ion migration path. The capacitor formed under this process has a more uniform heat distribution and lower internal stress during high-temperature operation, thus exhibiting "no hot spots" in thermal imaging tests, which is also reflected in its stable performance output. In contrast, Comparative Example 6 uses atmospheric pressure static injection, which is difficult to overcome the bubble barrier in the capillary channels under the complex internal structure of the device, resulting in insufficient liquid filling, leaving void areas, leading to local temperature rise and a decrease in electrochemical performance.

[0167] From an overall mechanism perspective, the high-temperature stability achieved stems from the synergistic effect of electrolyte composition and electrolyte injection technology: at the material level, a durable dielectric environment is constructed by introducing highly polar and thermally stable organic solvent components; at the process level, vacuum injection ensures interface uniformity and consistent heat transfer. This combination not only enhances the long-term heat resistance of the device but also significantly reduces the failure rate, providing stable support for industrial applications under high-temperature conditions. Experimental results fully validate the practical value of this design strategy in the development of high-reliability capacitors.

[0168] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fast-charging and discharging aluminum electrolytic capacitor, comprising a wound capacitor core, an aluminum shell, an electrolyte, and lead terminals, wherein the capacitor core is formed by layering and winding an anode aluminum foil, a cathode aluminum foil, and electrolytic paper, characterized in that, The anode aluminum foil is a high specific capacitance aluminum foil that has undergone anodizing treatment, with a thickness of 0.06-0.08 mm and an oxide film thickness of 500-700 nm; The electrolytic paper has a thickness of 0.015-0.020 mm and a density of 1.2-1.4 g / cm³. 3 ; The electrolyte comprises, by mass proportions: Propylene glycol 30-40 parts, γ-butyrolactone 20-30 parts, azelaic acid 5-10 parts, guanidine nitrate 5-10 parts, deionized water to make up to 100 parts; The capacitor core is installed in an aluminum housing and sealed with epoxy sealant.

2. The fast-charging and discharging aluminum electrolytic capacitor according to claim 1, characterized in that, The surface specific volume of the anode aluminum foil is 4000-6000 μF / cm. 2 .

3. The fast-charging and discharging aluminum electrolytic capacitor according to claim 1, characterized in that, The inner diameter of the aluminum shell is 12-20mm, and the length is 20-50mm.

4. The fast-charging and discharging aluminum electrolytic capacitor according to claim 1, characterized in that, The winding tension of the capacitor core is controlled at 0.3-0.5N.

5. A fast-charging and discharging aluminum electrolytic capacitor according to claim 1, characterized in that, The fast-charging and discharging aluminum electrolytic capacitor further includes a heat pipe heat dissipation structure disposed inside the aluminum casing.

6. A method for preparing a fast-charging and discharging aluminum electrolytic capacitor, characterized in that, The method for preparing a fast-charging and discharging aluminum electrolytic capacitor according to any one of claims 1-5 comprises the following steps: S1. Provide high-purity aluminum foil, perform electrolytic etching and anodizing treatment to form an anodic aluminum foil with a thickness of 0.06-0.08mm, and form an oxide film with a thickness of 500-700nm; S2, cutting thickness 0.015-0.020mm, density 1.2-1.4g / cm³ 3 Electrolytic paper; S3. The anode aluminum foil, cathode aluminum foil and electrolytic paper are alternately stacked and wound into a capacitor core; S4. Install the capacitor core into the aluminum casing; S5. Vacuum filling is performed using the electrolyte with the mass ratio of the fast-charging and discharging aluminum electrolytic capacitors as described above. S6. Perform phased aging charging by current limiting. The initial charging voltage is 70-80% of the rated value, and then gradually increases to the rated voltage. The aging temperature is 70-90℃, and the duration is 8-24 hours. S7. Finally, the packaging is completed and the finished product is formed.

7. The method for preparing a fast-charging and discharging aluminum electrolytic capacitor according to claim 6, characterized in that, In step S1, the electrolytic etching of the aluminum foil uses a mixed electrolyte of aluminum chloride and hydrochloric acid, with an etching voltage of 12-20V and a temperature of 50-65℃.

8. The method for preparing a fast-charging and discharging aluminum electrolytic capacitor according to claim 6, characterized in that, The electrolyte used in the anodizing step of step S1 is a mixed solution of 2-5 parts oxalic acid and 0.5-2 parts tartaric acid, with the pH controlled at 4.5-5.

5.

9. The method for preparing a fast-charging and discharging aluminum electrolytic capacitor according to claim 6, characterized in that, In step S5, the vacuum level during vacuum infusion is controlled between -0.09 and -0.095 MPa, and the settling time after infusion is 15-30 minutes.

10. The method for preparing a fast-charging and discharging aluminum electrolytic capacitor according to claim 6, characterized in that, In step S6, the voltage increase gradient during the aging charging process is 5-10V every 30 minutes, and the charging current is less than 5mA.

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